C # obtain the first day of the current month and the last day to calculate the number of days between the two dates,

C # obtain the first day of the current month and the last day to calculate the number of days between the two dates,

Obtain the first and last days of the current month.

DateTime now = DateTime. Now; DateTime firstDay = new DateTime (now. Year, now. Month, 1); DateTime lastDay = firstDay. AddMonths (1). AddDays (-1 );

Calculate the number of days between two dates

DateTime start = firstDay; DateTime end = lastDay; TimeSpan ts = end. Subtract (start); ts. Days;

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Thanks to the new ideas provided on the second floor, we will do a subtraction and an addition. You can see the code written on the second floor.

Date. AddDays (double) (1-Date. Day ))

Easy to understand, but easy to disassemble

Private void button#click (object sender, EventArgs e) {DateTime date = DateTime. now; double day = 1-date. day; DateTime firstDay = date. addDays (double) (1-date. day); MessageBox. show (firstDay. toShortDateString ());}

Now my date is, the value of the variable day is-18

AddDays is defined as "adding the specified number of days to the value of this instance". In this way, 19 + (-18) = 1. The idea is quite good, I sincerely thank @ diyun for his new thoughts.